Medical treatment of various illnesses or diseases commonly includes the use of one or more devices. Two types of devices that commonly used to repair various types of body passageways are expandable grafts or stents (device). An expandable graft often contains one or more materials used in creating a mock lumen. These devices have been implanted in various areas of the mammalian anatomy. One purpose of a stent is to open a blocked or partially blocked body passageway. When a stent, graft, and/or other suitable device is used in a blood vessel, the stent, graft, and/or other suitable device is used to open the occluded vessel to achieve improved blood flow which is necessary to provide for the anatomical function of a tissue mass or organ. The procedure of opening a blocked or partially blocked body passageway commonly included the use of one or more stent, graft, and/or other suitable devices in combination with other accessory devices such as, but not limited to, an introducer sheath, a guiding catheter, a guide wire, an angioplasty balloon, etc. Similarly grafts have been used to open a blocked or partially blocked body passageway in addition to providing the added benefit of a mock lumen. The mock lumen has been useful in excluding dissections of the vasculature, encapsulating vulnerable plaque, and/or to exclude blood flow into vascular malformations.
Various physical attributes of a stent and/or graft contribute directly to the success rate of the device. These physical attributes included but are not limited to radiopacity, hoop strength, radial force, thickness of the device, dimensions associated with the device or accessory product required to deliver, biocompatibility of the materials, the influence of the device on the reoccurrence of the disease, and the ability to redirect blood flow. Cobalt and chromium and stainless steel alloys have been commonly used to form stents and/or grafts and Polytetrafluoroethylene (PTFE) has been commonly used as a graft material. These materials have been commonly used since such materials having a known history of safety and biocompatibility.
These materials however have limited physical performance characteristics as to size, strength, weight, bendability, biostability, radiopacity, and incorporation of the device. The materials commonly used to form prior stents and/or grafts are biostable materials that remain as a permanent implant in the blood vessel long after the stent and/or graft had achieved its function. As such, the continued presence of the device in the blood vessel is associated with an increased risk of thrombosis, in-stent restenosis, vascular narrowing, restenosis in the blood vessel at the location of the device, and/or reoccurrence of the vascular malformation. The presence of the device in the blood vessel also created a potential obstruction to later medical procedures attempting to correct problems in a body passageway upstream from the device. Devices were also prone to fracturing over time, especially when implanted in regions exposed to bending (e.g., leg, arms, neck, etc.). The repeated bending of the device has resulted in one or more portions fracturing creating emboli, and/or an increased rate of thrombosis. These fractures (e.g., strut fractures, fractures in graft material, etc.) could result in damage to the blood vessel and/or one or more regions of the vascular system downstream of the device.
The present invention is generally directed to a device that is at least partially formed of novel biodegradable or bioabsorbable polymer. The device of the present invention can also include one or more agents. The one or more agents can be used to enhance one or more physical properties of a device so as to improve the success rate of such device. The device can be at least partially formed by using microfabrication and/or micromachining technology used in creating Micro-Electro-Mechanical Systems (MEMS), coating technologies, and/or molding processes so as to overcome several of the past problems associated with such devices. The terms “biodegradable” or “bioabsorbable” are used interchangeably in this invention.